This invention relates to apparatus for inspection of persons and more particularly to a walk-in inspection apparatus for producing air samples containing vapors of selected compounds such as explosives or drugs carried by a person.
Systems are known for acquiring air samples from subjects for detection of substances which emit vapors. For example, U.S. Pat. No. 4,202,200 describes apparatus for detecting explosives including an open-ended tunnel with two opposed pairs of apertures spaced at different distances along the tunnel walls. Air is circulated across the tunnel and through ducts connecting the apertures, and explosives detectors in one or more of the ducts detect vapors of explosives stripped from a person or vehicle positioned in, or passing through, the tunnel.
Systems of the type disclosed in the above-referenced U.S. Pat. No. 4,202,200 offer savings in time and labor when compared to hand-held sensors which are moved over a vehicle or the clothing of a person to be inspected. However, these automatic systems may result in the sampling of a non-representative portion of the air flowing past a subject, or the sampling of air flowed over less than the entire body of a person. Such incomplete sampling presents a risk of failure to detect concealed explosives or other substances. Also, the systems use similar arrangements for both vehicles and persons, and may be perceived as intimidating or quite uninviting places by people being screened. Moreover, diffusion of vapors into the collection air stream may be inadequate to provide samples containing concentrations of substances sufficient for their detection.
An object of the present invention is to provide an improved walk-in system for producing air samples by flowing air over, and collecting it from, essentially the entire body of a person during screening for selected vapor-emitting materials.
It is an object of the invention to provide a walk-in apparatus which minimizes the inconvenience to persons being sampled.
It is an object of the invention to provide apparatus for producing air samples including a walk-in booth which persons to be screened perceive as non-threatening and as inviting entry.